A two-stroke, or two-cycle, engine is a type of internal combustion engine which completes a power cycle in only one crankshaft revolution and with two strokes of a piston. This is accomplished by the end of the combustion stroke and the beginning of the compression stroke happening simultaneously and performing the intake and exhaust functions at the same time. Two-stroke engines often provide high power-to-weight ratio. Two-stroke engines may be either a gasoline, spark ignition engine, or a diesel, compression ignition engine.